The basic concept of a sensor automatically monitoring its operational capability, i.e., self-validating performance, is generally recognized. An attempt is made to continuously monitor and self-validate the sensor's performance to determine the health of the sensor. The process of self-validation involves the continued assessment of a combination of: 1) reviewing physical parameters obtained real-time by means of electronic circuitry to obtain actual measurement data; and 2) utilizing a combination of statistical tools to estimate and predict a measurement value at a given time in the process and compare the predicted measurement value to the actual measurement data. Self-validation processes used by others include ARMA (Auto Regression Moving Average), LCSR (Loop Current Step Response), and Power Spectrum Density determination. The failure or success of any of these processes presupposes properly functioning sensor circuitry.
However, in many sensors, and particular thermocouples, the actual cause for failure is directly related to the physical bonding between the thermocouple sensor element and the attachment surface. As a consequence, conventional self-validating techniques may fail to reliably identify the bonded/debonded condition that directly leads to sensor failure.
For the reasons stated above, and for other reasons that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternative approaches to thermocouple validation.